This disease appears to be more important each year. It is not clear to me why. This article reviews Plectosporium of pumpkin, sometimes called white speck. I would rank Plectosporium blight behind powdery mildew, bacterial leaf spot and Phytophthora blight in economic damage caused. The occurrence of this disease is usually sporadic. However, when it[Read More…]
Dan Egel
Downy mildew was observed on pumpkins in Daviess, Knox and Washington County. Evenings and mornings with heavy dews and fogs may help the disease to spread. Whether to apply fungicides for this disease will depend in part on when growers plan to harvest. In addition to the cucurbit downy mildew outbreaks reported in the last[Read More…]
Downy mildew has been observed in LaPorte County in northern Indiana on cucumber. In addition, downy mildew on cucumber has been reported in southern Kentucky and on watermelon in the Kansas City area of Kansas. Growers in northern Indiana should manage for downy mildew on valuable cucurbit crops (Figure 1). Growers throughout the state should[Read More…]
On a sandy hillside in a watermelon field, we noted vines that, from a distance, appeared undersized compared to the vines in the flats. Upon closer inspection, some of the vines had either wilted or a portion of the plant had wilted. The wilted vines had discolored vascular tissue. These vines were affected by Fusarium[Read More…]
What is causing the spots on the watermelon leaf? A) anthracnose B) early blight C) a contact herbicide The answer is that the leaf above has been affected by a contact herbicide. The herbicide caused lesions upon contacting the leaf. However, there was no growth of the lesion and no yellowing of the leaf[Read More…]
Downy mildew has been observed on cucumber in Berrien County in extreme southwestern Michigan and in Monroe County in extreme southeast Michigan. The downy mildew spores that cause disease on cucumber will cause disease on cantaloupe and may cause disease on other cucurbits such as pumpkin and watermelon. The forecast is for the spread of[Read More…]
This disease was observed in a home garden recently on table beet (Figure 1). I was surprised considering how dry it has been. Cercospora leaf spot also affects swiss chard. Symptoms include circular leaf spots that may have a reddish margin. The center of the lesions may start off a light brown and turn to gray after the fungus (Cercospora beticola) begins to sporulate.[Read More…]
Question: Why are the water droplets arranged so evenly around the edge of this cucurbit leaf? Answer: The water droplets came out of pores that are at the edge of the leaf where a vein ends. The pores are called hydathodes. The droplets form through the process of guttation. Guttation is when the water pressure[Read More…]
Tomato brown rugose fruit virus (ToBRFV) is making headlines and eliciting USDA action. Growers need to learn more about ToBRFV biology, symptoms and control. Tomato brown rugose fruit virus (ToBRFV) is a newly identified virus affecting tomato, pepper and possibly their relatives. ToBRFV first appeared in Israel in 2014. Since then, it has shown up[Read More…]